Fasteners used in aircraft and other industrial applications include blind rivets, blind bolts, lock bolts, and similar fasteners. These fasteners normally are inserted through prepared holes in work pieces that are to be joined to each other and installed in a manner that presses the work pieces together to ensure that there is no relative motion between the work pieces after the fasteners are installed. Generally, these fasteners are installed using a hydraulically activated gun or pulling tool that applies a tensile force to one part of the fastener and a compressive force to another part. A pulling head, operative to transmit both the tensile and compressive forces to a particular type and size of fastener, is attached to the gun or tool.
Often, a single gun or tool can be used with a variety of pulling heads to install a variety of fasteners. An adapter is used to join the pulling head to the tool or gun. Typically, an adapter is a tube or sleeve and an accompanying shaft, with each having screw threads on one end mateable with threads on the tool or gun and screw threads on the other end mateable with threads on the pulling head.
In use, it is often necessary to use an offset head with the pulling axis of the head displaced laterally from but parallel to the pulling axis of the tool, a right angle or other angled head with the pulling axis oriented at an angle other than parallel relative to the tool, or a straight pulling head for special use designed to fit into a relatively tight space. In these cases, the position of the head must be shifted or rotated relative to the tool to place fasteners in different locations, for example, above or below the shoulder of the installer or to one side or the other of the installer. Such repositioning of the pulling head relative to the tool is presently accomplished by loosening the jam nut on the pulling head, then rotating the head, and then locking the jam nut. The threads used to connect the draw bolt of the pulling head to the puller shaft of the adapter usually have a different pitch than the threads used to connect the outer portion of the pulling head to the outer sleeve of the adapter. Thus, each time the head is rotated for use in a different orientation, the positions of the draw bolt and the adapter puller shaft and the positions of the outer portion of the pulling head and the outer sleeve of the adapter are shifted relative to each other along the lengthwise axis of the tool. After a few reorientations, the tool can become inoperative because the relative axial positions of the draw bolt and puller shaft in relation to the axial positions of the outer portion of the head and the outer sleeve of the adapter do not allow the full range of relative axial motion needed to install a fastener. As a result, the pulling head often malfunctions. The position of the draw bold relative to the puller shaft, and the position of the outer portion of the head relative to the outer sleeve of the adapter, usually cannot be detected by looking at the assembled tool and pulling head. If a malfunction occurs, and the tool/head assembly is not damaged, the tool/head assembly must be fully disassembled and then reassembled by the operator, who must insure that all threaded parts are attached properly in accordance with industry standards.
The frequent loosening and tightening of the adapter relative to the pulling tool and the pulling head causes excessive wear on the complete assembly, requiring repairs to or replacement of the pulling tool, the pulling head, or the adapter. Further, repositioning the pulling head relative to the tool takes significant time, which reduces productivity. In addition, workers who use the tools and pulling heads are prone to repetitive use injuries from the frequent repositioning of the pulling head relative to the tool.
Thus, there is a need for an improved adapter that reduces tool wear, decreases the time required for repositioning the pulling head relative to the tool, and reduces the likelihood of repetitive motion injuries to workers using the tool.